CA2049770A1 - Production of diethanolamine derivatives and their intermediates - Google Patents

Abstract

ABSTRACT

Production of Diethanolamine derivatives and Their Intermediates A method of producing diethanolamine derivatives or acid salts thereof according to the reaction scheme:

Description

- 1 - 2(~4~3~7~) .

Production of Diethanolamine derivatives and Their Intermediates This invention relates to a method of preparing diethanolamine derivatives useful as antiarrhythmic agents and to new intermediates employed in the method.
More specifically, the present invention relates to an industrially advantageous method of preparing a diethanolamine derivative of the formula, N-CH2CH2NH2 (I) lS wherein R1 stands for alkyl carbamoyl group, and an acid addition salt thereof, and to diethanolamine derivatives, which are useful novel intermediates in the above method, of the formula;
~-OCH2CH2 \
N-CH2-CN (VI) wherein R stands for hydrogen or alkyl carbamoyl group.
Arrhythmia is one of the diseases often observed especially in old people, and when it takes a serious turn, the patient's life becomes in danger. Recently, coronary diseases are rapidly increasing, and a serious concern is directed to counter-measures to fatal arrhythmia brought by those diseases.
As antiarrhythmic agents, various pharmaceutical products have been developed and used clinically.
Ho~ever, among those agents, since differences in effectiveness are observed depending on conditions of diseases due to complicated causes of arrhythmia, antiarrhythmic agents effective for broadened types of arrhythmia and ~ith less side effects have been sought for.

- 2 - ~ ~4~77~

As a part of these research works, diethanolamine derivatives (I) having a unique structure and their acid addition salts were found and reported [USP
4,98~,130].
The compound (I), having symmetric structure relative to the nitrogen atom of the tertiary amine, can be synthesized by N-alkylation of diethanolamine and carbamoylation of two hydroxyl groups. In the specification of USP 4,987,130, therefore, there is disclosed a method of producing diethanolamine derivatives (I), which comprises protecting -the secondary amino group with t-butyloxycarbonyl group tBoc group) to distinguish essentially two reaction points of diethanolamine, i.e. secondary amino group and the two hydroxyl groups, from each other, carbamoylating the two hydroxyl groups, then removing the Boc group, i.n-troducing phthalimido alkyl chain by ~I-alkylation, and then removing the phthaloyl group.
This method can be hardly considered industrially ~0 advantageous for the synthesi.s of diethanolamine derivatives (I), because both the Boc group and the phthaloyl group employed as protecting groups of the secondary amino group and the primary amino group are expensive and, besides, the number of reaction steps are relatively more, since they include protecting and deprotecting reactions.
The present i.nvention relates to an industrially advantageous method of preparing diethanolamine derivatives (I) or an acid salt thereof which is useful as an antiarrhythmic agent, without any step for introducing and removing protecting groups and having less in the number of reaction steps than prior methods, and diethanolamine derivatives (VI) to be employed as useful novel intermediates in the above method.
The present invention provides - 3 - 2~ 7~

(1) a method of preparing a diethanolamine derivative (I) or an acid addition salt thereof, which is characterized by subjecting a compound (V) of the formula, N-CH2CN (V) wherein R stands for alkylcarbamoyl group, to catalytic reduction, (2) a method of preparing a diethanolamine derivative (I) or an acid addition salt thereof, which is characterized by allowing a compound of the formula, HOCH2CH2 ~
N-CH2CN (IV) to react with alkyl isocyanate, then subjecting the resultant compound (V) to catalytic reduction, (3) a method of preparing a diethanolamine derivative (I) or an acid addition salt thereof, which is characterized by allowing diethanolamine of the formula, HOCH2CH2 ~
NH (II) to react with an acetonitrile derivative (III) of the formula, XCH2CN (III) wherein X stands for a leaving group, then allowing the resultant compound (IV) to react with alkyl isocyanate, then subjecting the resultant compound (V) to catalytic reduction, and (4) the compounds (IV) and (V).
Examples of the alkyl carbamoyl group shown by R' - 4 - 2~7~

and R include n-lower alkyl carbamoyl groups having about 1 to 6 carbon number at its alkyl moiety such as methylcarbamoyl, ethylcarbamoyl, n-propylcarbamoyl, isopropylcarbamoyl, n-butylcarbamoyl, isobutylcarbamoyl, sec-butylcarbamoyl, tert-butylcarbamoyl, n-pentylcarbamoyl, isopentylcarbamoyl, neopentylcarbamoyl, tert-pentylcarbamoyl, n-hexylcarbamoyl, isohexylcarbamoyl, neohexylcarbamoyl and tert-hexylcarbamoyl, and among them, n-butyl carbamoyl group is preferable.
Examples of lea~ing groups shown by X include halogen such as fluoro, chloro, bromo and iodo, and a lower 1-4C alkoxy group such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxyl, and halogen is preferable, especially chloro and bromo are preferable.
As alkyl isocyanate, mention is made of a lower alkyl isocyanate having about 1 to 6 carbon number at its alkyl moiety such as methylisocyanate, ethylisocyanate, n~propylisocyanate, isopropylisocyanate, n-butylisocyanate, isobutylisocyanate, sec-butylisocyanate, tert-butylisocyanate, n-pentylisocyanate, isopentylisocyanate, neopen-tylisocyanate, tert-pentylisocyanate, n-hexylisocyanate, isohexylisocyanate, neohexylisocyanate and tert-hexylisocyanate.
As the acid addition salts of diethanolamine derivatives (I), mention is made of pharmacologically acceptable inorganic acid salts S-lCh as hydrochloride salts, sulfuric acid salts, nitric acid salts and phosphate and organic acid salts such as carbonate, sulfonate and sulfinate, and, among them, hydrochloride salts (dihydrochloride salts) are preferable.
In the following, the method of this invention is described in detail.

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First, by allowin~ diet.hanolamine (II) to react with a compound represented by the formula (III), the compound (IV) is produced.
Diethanolamine (II) has two reaction points, i.e.
secondary amino ~roup and two hydroxyl ~roups, and it has been known that the former is more excellent in nucleophilic property than the latter.
This reaction is usually conducted in the presence of an acid acceptor. And, examples of an acid acceptor include tertiary amine such as triethylamine, N,N-dlisopropylethylamine, tri-n-propylamine, tri-n-butylamine, etc., an aromatic amlne such as pyridine, an inorganic base such as ammonia water, sodium hydroxide, sodium bicarbonate, sodium carbonate, etc.
or a base such as basic ion-exchange resin. The reaction may usually be conducted in a solvent. And, examples of the solvent include aliphatic hydrocarbon halogenides such as dichloromethane, dichloroethane, chloroform, etc., alcohols such as methanol, ethanol, etc., ethers such as dioxane, tetrahydrofuran, and, besides, acetone, acetonitrile, N,N-dimethylformamide, etc., and among them use of acetonitrile is most desirable. An acid acceptor is used at a ratio of 1 to lO mols., desirably 2 or 3 mols. relative to one mole of a diethanolamine (II). An acid acceptor may be dissolved in a solvent before the reaction. An acetonitrile derivative (III) is used at a ratio of 1 to 5 mols., desirably 1 to 3 mols. relative to one mole of (II). The reaction temperature is usually at -70 to 100C, desirably 0 to 80C. The reaction time is usually 1 to 2~ hours, desirably 1 to 5 hours~ The reaction may for example be conducted by adding an acetonitrile derivative (III) dropwise at a ratio of 1 to 5 mols., desirably 1 to 3 mols. relative -to one mole of (II), at -50 to 80C, desirably 0 to 30C, and then heating for 1 to 5 hours at 30 to 80C, desirably 30 to - 6 ~ 4~77~) 50C.
While the reaction mixture can be subjected to the subsequent reaction after processing by a conventional manner such as filtration and concentration then isolating and refining the compol~nd (IV) by means of an alumina column chromatography, the reaction can be allowed to proceed in the manner of one-pot by adding alkyl isocyanate continuously without isolating -the compound (IV).
On the other hand, there is a method which comprises using diethanolamine (II) as reaction substrate, solvent and acid acceptor. In this case, the reaction is conducted by using diethanolamine (II) at a ratio of 2 to 10g, desirably 2 or 3g rela-tive to lg of th~ acetonitrile derivative (III). The reaction temperature is usually at -70 to 100C, desirably 0 to 80C. The reaction time is usually 1 to 24 hours, desirably 1 to 5 hours. For example, the reaction may be conducted by adding (III) to (II) dropwise at a temperature range between -50 to 80C, desirably 0 to 50C, and then heating for 1 to 5 hours at 30 to 80C, desirable 30 to 50C. Compound (IV) can also be isolated by extrac-tion by adding to the resultant reaction mixture an aliphatic hydrocarbon halogenide such as dichloromethane, dichloroethane, chloroform, etc. or an ether such as dioxane, tetrahydrofuran, etc.
The reaction for obtaining the compound (V) from the compound (IV) and alkyl isocyanate is conducted by using a solvent other than alcohols, for example an aliphatic hydrocarbon halogenide such as dichloromethane, dichloroethane~ chloroform, etc., ethers such as dio~ane, tetrahydrofuran, etc., and any other suitable solvent such as acetone, acetonitrile, N,N-dimethylformamide, etc., or, depending on cases, the reaction is conducted in the absence of solvent.
Usually, reaction between alcohols and isocyanates does - 7 - ~ 7~

not require the presence of a base, but the present reaction can be allowed to proceed advantageously by adding to the reaction system a catalytic amount or a not less than the stoichiometric amount of a tertiary amine such as triethylamine, N,N-diisopropylethylamine, tri-n-propylamine, tri-n-butylamine, etc., an aromatic amine such as pyridine, etc., an inorganic base such as ammonia water, sodium hydroxide, sodium bicarbonate, sodium carbonate, etc., or a base such as a basic ion-exchange resin. In the present reaction, since thecompound (IV) reacts with alkyl isocyanate slowly, addition of a suitable amount of a relevant base is preferable. The reaction temperature is usually at -70 to 100C, desirably 0 to 80C. The reaction time is usually 1 to 24 hours, desirably 1 to 5 hours. The reaction can be conducted for 1 to S0 hours at temperatures ranging from 0 to 60C, desirably 30 to 50C, after adding to the mixture of compound (IV) and the base dropwise alkyl isocyanate at a ratio of 2-5 times as much mol., desirable 2-2.5 times as much mol.
relative to compound ~IV) at temperakures ranging from -20 to 80C, desirably 0 to 50C. While the compound (V) can be isolated by processing the reaction mixture in a conventional manner such as separation, it can be refined, when necessary, by means of an alumina column chromatography or a silica gel column chromatography. And, the next reaction can be allowed to proceed continuously with the reaction mixture of the compound (V).
The compound (I) is produced by subjecting the compound (V) to catalytic reduction. The catalytic reduction can be conduc~ed in the conventional manner.
As methods of reducing nitrile to amine, there have been known a method using lithium aluminum hydride (J. Am. Chem. Soc., 73, 2~2 (1951))t catalytic reduction using Raney nickel (J. ~m. Chem. Soc., 66, - 8 ~

876 (1944)), and elPctrolytic reduction (JPA S55(1980)-76084) and diborane reduction, among others. For the reduction of compound (V) to compound (I), catalytic reduction is employed advantageously.
As the solvent for catalytic reduction, use is made of lower(1-4C) alcohols such as methanol, ethanol, propanol, etc., ethers such as dioxane, tetrahydrofuran, etc., aromatic hydrocarbon such as benzene, toluene, xylene, etc., ethyl acetate, acetic acid, N,N-dimethylformamide, etc. or a mixture of them, desirably, a mixture of lower(1-4c) alcohols and aromatic hydrocarbon. As the catalyst, while use is made of Raney nickel or Raney cobalt, modified Raney nickel or modified Raney cobalt can also be employed.
The modified Raney nickel or modified Raney cobalt is prepared by, for example, the following method.
A Raney nickel or Raney cobalt alloy prepared by adding to nickel or cobalt a metal such as iron, chromium, lead, manganese, etc. in an amount of about 0.01-3% in terms of atomic ratio relative to the nickel or cobalt is developed with potassium hydroxide or sodium hydroxide. The amount of the catalyst ranges from about 0.5 to 60 weight ~ re:Lative to compound (V~, desirably 10 to 40 weight %.
In this reaction, besides the catalyst, hydroxide or alcoholate of an alkali metal or al.kaline earth metal is preferably added to the reaction system. As the hydroxide, mention is made of an al]cali metal hydroxide such as sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. and an alkaline earth metal hydroxide such as calcium hydroxlde, barium hydroxide, magnesium hydroxide, etc. The amount of the hydroxide to be added to the reaction system ranges from about 50 to 1000 mg equivalent, preferably 100 to 500 mg equivalent, as the metal relative to 100 g of compound ~V). The hydrogen pressure for the 9 ;~9L977~

hydrogenation of nitrile is normal or an elevated pressure in general, which ranges preferably from about 2 to 150 kg/cm2 when the reaction is conducted on an industrial scale. No particular temperature range is required for the reaction in general, so long as the reaction is conducted at about 20C or higher, but preferably 30 to 150C, especially 50 to 100C. The reaction time varies with the amoun-t of catalyst, hydro~en pressure and reaction temperature, which ranges from about 1 to 10 hours.
The compouncl (I) thus obtained can be easily isolated and purified by a known means of separation and purification such as separation and silica gel column chromatography. An acid salt of the compound (I) can be prepared by adding an acid to the compound (I). As the acid, mention is made of inorganic acid such as hydrochloride, sulfuric acid, nitric acid, and phosphoric acid and organic acid such as carbonic acid, sulfonic acid and sulfinic acid. For example, hy adding to the compound (I) an ethanolic hydrogen chloride or an isopropanolic hydrochloride salts (dihydrochloride salts) of the compound (I) can be obtained as crystals of high quality.
The compound (I) and an acid salt thereof which are prepared by the present invention, are used for a mammal including human as antiarrhythmic agents. ~he compounds (I) or their salts can be safety administered orally or parenterally, as such or after being processed into such dosage forms as powder, granule, tablet, capsule, suppository and injectabl~ solution by means of the conventional procedures with use of pharmacologically allowable carriers, excipients, diluents, etc [USP 4,987,130].
According to the present invention, as compared with conventional methods, the compound (I) and an acid addition salt thereof can be produced without any step 1 o - ;2 ~ 7~

for introducing and removing protecting groups, with less reaction steps, lower production cos~, short time, and higher yield. Thus, the method of this invention is remarkably advantageous from the industrial point of view. The compounds (IV) and (V) are new compounds, which are essential intermediates for the above-mentioned industrially advantageous method for the production of a diethanolamine derivatives (I) or its acid addition salts.
By the following working examples, the present invention will be concretely described, but i-t should be understood that the invention is not limited thereto.
In working examples, room temperature means 20 to 25C.
Example 1 Preparation of N,N-bis(2-hydroxyethyl)aminoacetonitrile (IV) a) In 15 mQ of methanol were dissolved 2.5 ~ of diethanolamine (II) and 7 mQ of triethylamine. To the solution was added dropwise 3.9 g of bromoacetonitrile while stirring under cooling, then the mixture was stirred for 3 hours at room temperature. The reaction mixture was concentrated under reduced pressure. To the concentrate was added 15 mQ ofdichloromethane, then insolubles were filtered off. The filtrate was concentrated under reduced pressure. The concentrate was subjected to an alumina column chromatography, followed by elution with dichloromethane. Fractions containing the object compound were combined, then the solvent was distilled off under reduced pressure to leave 3.3 g (96% yield) of a colorless clear oily substance (IV).
IR(Neat)cm 1 3400, 2250(w) NMR(9OMHz, DMSO-d6)~: 2.56(4H,t,J=6Hz), 3.48(4H,t,J=6Hz), 3.79(2H,s) 97~3 b) To 70 g of diethanolami.ne (II) was added dropwise 24 g of chloroacetonitrile while stirring at 50C or below taking one hour, then the mixture was stirring for one hour at 50C. The reaction mixture was cooled, which was subjected to extraction with 200 mQ of tetrahydrofuran. To the oily portlon of the lower layer was separated, which was subjected to extraction twice with 70 mQ each portion of tetrahydrofuran. Thus extracted tetrahydrofuran layers were combined and dried over anhydrous sodium sulfate and anhydrous potassium carbonate, followed by distilling off the solvent under reduced pressure to leave 45.6 g of a pale yellow clear oily substance (IV). (Apparent yield 99.6%, content 90%) lS Example 2 Preparation of N,N-bis(n-butylcarbamoyloxy~
ethyl)aminoacetonitrile (V') a) In 50 mQ of acetonitrile were dissolved ~ g of the compound obtained in Example l~a) and l9 mQ of triethylamine. To the solution was added 13.8 g of n-butyl isocyanate, and the mixture was stirred for 12 hours at room temperature. The reaction mixture was concentrated under reduced pressure, then the concentrate was dissolved in 200 mQ of ethyl acetate 2S and washed with 100mQ of water. The resultant was washed with 100 mQ of a lN-NaO~ aqueous solution and 100 mQ of lN-HCl aqueous solution, which was then washed with 100 mQ of water and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure, then the residue was subjected to a silica gel column chromatography, followed by elution with dichloromethane. Fractions containing the object compound were combined, then the solvent was distilled off under reduced pressure to leave 17.1 g (90% yield) of a colorless clear oily substance (V').
IR(Neat)cm 1 2240(w), 1710 - 12 ~ ~ 7~

NMR(9OMHz,CDC13)~: 0.92(6H,t,J=7Hz), 1.10-1.96(8H,m), 2.86(4H,t,J=6Hz), 3.17(4~,t,J=6~1z), 3.70(2H,s), 4.17(4H,t,J=6Hz) b) To 45.6 g (content 90%) of the compound (IV) obtained in Example l-b) was added 80 g of triethylamine, and the mixture was stirred. To the mixture was added dropwise slowly 78.6 g of n-butyl isocyanate at 50C or below, followed by stirring for 3 hours at 50C. The reaction mixture was concentrated under reduced pressure while distilling off triethylamine. To the residue was added 1.2 liter of isopropylether to make a solution. The solution was washed twice with 200 mQ of a lN-NaOH aqueous solution and twice with 200 mQ of a lN-HCl aqueous solution, followed by washing with 200 mQ of water and drying over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure to leave 102.5 g (apparent yield 9~.6%, content ~5%) of a pale yellow clear oily substance (V').
Example 3 One-pot preparation of N,N-bis(n-butylcarbamoyloxyethyl)aminoacetonitrile (V') from diethanolamine (II) a) In 15 mQ of dichloromethane were dissolved 2.5 g of diethanolamine (II) and 6.6 mQ of triethylamine. To the solution was added dropwise 4.5 g of bromoacetonitrile while stirring at 5 to 10C. The mixture was stirred for 1.5 hour at the same temperature range, then for one hour at room temperature. To the reaction mixture was added 5.9 g of n-butyl isocyanate, which was refluxed for 12 hours.
To the reaction mixture were added 100 mQ of dichloromethane and 50 mQ of water to form two layers.
The aqueous layer was re-extracted with 50 mQ of dichloromethane. The dichloromethane layers were combined, washed with 50 mQ of water and dried cver - 13 - ~ 7~

anhydrous sodium sulfa~e. The solvent was distilled off under reduced pressure to leave 9.0 g (apparent yield 111%, content 69%) of a reddish brown oily substance (V').
b) In 15 mQ of acetonitrile were dissolved 2.5 g of diethanolamine (II) and 6.6 mQ of t.riethylamine. To the solution was added dropwise 4.5 g of bromoacetonitrile while stirring at temperatures ranging from 5 to 10C. The mixture was stirred for 1.5 hour at the same temperature range, then or one hour at room temperature. To the reaction mixture was added 5.9 g of n-butyl isocyanate, and the mixture was left standing for two days at room temperature. The reaction mixture was concentrated under reduced pressure. To the concentrate were added 100 mQ of dichloromethane and 50 mQ of water to form two layers.
The aqueous layer was re-extracted with 50 mQ of dichloromethane. The dichloromethane layers were combined, washed with 50 mQ of a saturated aqueous solution of sodium bicarbonate and 50 mQ of water, then dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure to leave 8.9 g (apparent yield 109%, content 75%) of a reddish brown oily substance (V').
c) In 15 mQ of acetonitrile were dissolved 2.5 g of diethanolamine (II) and 6.6 mQ of triethylamine. To the solution was added dropwise, while stirring at temperatures ranging from 5 to 10C, 2.7 g of chloroacetonitrile. The mixture was stirred for 5 hours at room temperature, which was the left standing for 2 days at room temperature. To the reaction mixture was added 5.9 g of n-butyl isocyanate, and the mixture was stirred for 12 hours at room temperature, which was then left standing overnight. The reaction mixture was concentrated under reduced pressure, to which were added 100 mQ of dichloromethane and 50 mQ of - 14 - ~ 7~

water to form two layers. The aqueous layer was separated and re-extracted with 50 me of dichloromethane. The dichloromethane layers were combined, washed with 50 mQ of water, then dried over anhydrous anhydrous sodium sulfate. The solvent was distilled off under reduced pressure to leave 9.1 g (apparent yield 112%, content 71%) of a reddish brown oily substance (V').
Example 4 Preparation of 2,2'-[~2-aminoethyl)imino~diethanol bis(n-butylcarbamate) (I') and its dihydrochloride a) A 200 mQ-capacity autocJave was charged with a solution of 9.0 g of the compound (V') obtained in Example 3-a) in ~0 mQ of toluene, a solution of 80 mg of sodium hydroxide in 80 mQ of methanol and 3 g of Raney nickel. The reaction was allowed to proceed for 30 minutes at 80C under hydrogen pressure of 100 kg/cm . The reaction mixture was subjected to iltration, and the filtrate was concentrated under reduced pressure. To the concentrate was added 100 mQ
of dichloromethane r which was subjected to extraction with 100 mQ of lN-HCl twice. The extracted aqueous layers were combined and washed with 100 mQ of ethyl acetate. The aqueous layer was made alkaline with conc. ammonia water. Resultant precipitates were subjected to extraction with 100 mQ of dichloromethane.
The extract was washed with 50 mQ of a saturated aqueous saline solution, then dried over anhydrous sodium sulfate. The solvent was distilled off to leave about 7 g of the compound tI'). This product was dissolved in 70 mQ of isopropanol, to which was added 15 mQ of isopropanolic hydrogen chloride (7 mol }I~l/1 liter isopropanol), and the mixture was left standing - 35 overnight. Precipitating crystals were collected under reduced pressure, washed with 50 mQ of acetone, then - 15 - ~ 7~

dried at 40C under reduced pressure to afford 6.83 g [overall yield 68.5% from diethanolamine (II)] of dihydrochloride of the compound (I').
Elemental Analysis for C16H36C12N404 :
Calcd. : C, 45.82; H, 3.65; N, 13.36 Found : C, 46.07; Hr 8.79; N, 13.45 IR(RBr-disc)cm : 2400, 1685 NMR(9OMHz, D20)~: 0.86(6H,t,J=7Hz), 1.05-1.65(8H,m), 3.07(4H,t,J=6.5Hz), 3.25-3.75(~H,m), 4.35(4H,t,J=4.5Hz) b) In the same manner as in a) above, 8.9 g of the compound (V') obtained in Example 3-b) was subjected to reaction and treatment to give 7.07 g ~overall yield from diethanolamine (II) - 70.9%] of dihydrochloride of the compound (I').
c) A 500 mQ-capacity autoclave was charged with a solution of 20 g (content 82%) of the compound (V') obtained by the same manner as in ~xample 2-b) in 90 mQ
of toluene, a solution of 540 mg of sodium hydroxide in 180 mQ of methanol and 6.7 g o-f Raney nickel. The reaction was allowed to proceed for 3 hours at 60C
under hydrogen pressure of 9 kg/cm2. The reaction mixture was subjected to filtration, and the filtrate was concentrated under reduced pressure. To the concentrate were added 100 mQ of lN-HCl and 100 mQ of ethyl acetate. The ethyl acetate layer was separated, which was re-extracted with 100 mQ of lN-HCl. The extracted aqueous layers were combined, to which was added 110 mQ of lN-NaOH to make the solution alkaline (pH ca 12), then resulting precipitates were subjected to extraction with 150 mQ of ethyl acetate. The ethyl acetate layer was washed with 50 mQ of water, dried over anhydrous sodium sulfate, then the solvent was distilled off under reduced pressure to leave 17.1 g of the compound (I'). This product was dissolved in isopropanol, to which was added 35 mQ of isopropanolic hydrogen chloride (7 mol. HCl/l li.ter isopropanol), and - 16 - ~ ~ ~97 the mixture was left standing overnight at room temperature. Crystalline precipitates wers collected by filtration, washed with acetone and dried at 40C
under reduced pressure to give 16.7 g [yield in terms of purity from the compound (V') = 82.1%].

Claims (16)

1. A compound of the formula:

wherein R stands for hydrogen or an alkylcarbamoyl group.

2. A method of preparing 2,2'-[(2-aminoethyl)imino]
diethanol bis(alkylcarbamate) or an acid addition salt thereof, which comprises subjecting N,N-bis(alkylcarbamoyloxyethyl)aminoacetonitrile to catalytic reduction.

3. A method of preparing 2,2'-[(2-aminoethyl)imino]
diethanol bis(alkylcarbamate) or an acid addition salt thereof, which comprises reacting N,N-bis(2-hydroxyethyl)aminoacetonitrile with alkyl isocyanate, and then subjecting the resultant N,N-bis(alkylcarbamoyloxyethyl)aminoacetonitrile to catalytic reduction.

4. A method of preparing 2,2'-[(2-aminoethyl)imino]-diethanol bis(alkylcarbamate) or an acid addition salt thereof, which comprises reacting diethanolamine with a compound of by the formula:

[wherein X stands for a leaving group, reacting the resultant N,N-bis( 2-hydroxyethyl)aminoacetonitrile with alkyl isocyanate, and then subjecting the resultant N,N-bis( alkylcarbamoyloxyethyl)aminoacetonitrile to catalytic reduction.

5. A method of preparing N,N-bis( 2-hydroxyethyl)aminoacetonitrile, which comprises reacting diethanolamine with a compound of the formula:

wherein X stands for a leaving group.

6. A method of preparing N,N
bis(alkylcarbamoyloxyethyl)aminoacetonitrile, which comprises reacting N,N-bis(2-hydroxyethyl)aminoacetonitrile with alkyl isocyanate.

7. A method of preparing N,N-bis(alkylcarbamoyloxyethyl)aminoacetonitrile, which comprises reacting diethanolamine with a compound of the formula:

wherein X stands for a leaving group, and then reacting the resultant N,N-bis(2-hydroxyethyl)aminoacetonitrile with alkylisocyanate.

8. A compound as claimed in claim 1, wherein the alkylcarbamoyl group is a C1-6 alkylcarbamoyl group.

9. A method according to claim 2, wherein the alkyl is a C1-6 alkyl group.

10. A compound as claimed in claim 8, wherein the C1-6 alkylcarbamoyl group is a n-butylcarbamoyl group.

11. A method according to claim 9, wherein the C1-6 alkyl is a n-butyl group.

12. A method according to claim 5, wherein the leaving group is a halogen or a C1-4 alkoxy group.

13. Use of a compound of the formula:

wherein R stands for hydrogen or an alkylcarbamoyl group as an intermediate in the preparation of 2,2'-[(2-aminoethyl)imino]diethanol bis(alkylcarbamate) or an acid addition salt thereof.

14. A method according to claim 5, wherein the leaving group is chloro.

15. A method according to claim 14, wherein 2,2'-[(2-aminoethyl)imino]diethanol bis(n-butylcarbamate) is prepared.

16. A method for using of a compound of the formula:

wherein R stands for hydrogen or an alkylcarbamoyl group as an intermediate in the preparation of 2,2'-[(2-aminoethyl)imino]diethanol bis(alkylcarbamate) or an acid addition salt thereof.